There are no longer any tires that will work on this. We use to have a tire called a "Twin tire" where two tires were ran on the same automotive rim such that you had 8 tires on your car. These tires worked great as sidecar tires, they came in either a 125 90 16 or a 125 85 16 and yes we had M + S ratings however as it has been about 12 years since they were last made if you were able to find any more I can not recomend running them as they are now quite old. When they were being discontinued when we found out about it we purchased 750 of these tires but have been sold out for years now.
Jay G
DMC sidecarswww.dmcsidecars.com
866-638-1793jay@dmcsidecars.com

Alternately, I could try to "relace" (of that's the term to use with comstar wheels) the CB900C hub to a 15" comstar rim and run a VW tire. But I have no idea what rims will fit what hubs with what "spokes". D:

The CX500 (which shares the same final drive as the CB900C) came in a version with an 18" rim, which I could run my lovely $35 shinkos on and just burn through them, but they all had a drum brake and I think the bearings/axle are a different size. :/

Alternately, I could try to "relace" (of that's the term to use with comstar wheels) the CB900C hub to a 15" comstar rim and run a VW tire. But I have no idea what rims will fit what hubs with what "spokes". D:

I have a set of plates for the comstar wheels that convert them to spoke type wheels that can be laced to what ever you want. $100 for the plates. No idea where they came from or if they are a one off.
Jay G
DMC sidecars
866-638-1793www.dmcsidecars.comjay@dmcsidecars.com

Interesting. Last night I was looking at some CX500 forums where they'd done the plate/spoke conversion, and was trying to figure out if I had good enough equipment/skills to make some. :P

They're also fond of drilling out the rivets and "relacing" comstars with sleeved aircraft bolts and loctite. Nobody has posted any wheel failures from doing that so.....

I think attempt #1 will involve getting a CB900F 18" rear rim off of fleabay and trying to "lace" it up to the 900C hub.... Then I'll have a larger selection of cheap tires D/S to blow through. I /think/ it'll fit inside the swingarm...... This seems more attractive to me than spoke maintenance. I know, it seems a little silly to run D/S tires on a big bike like that, and I don't intend to be blazing any trails over non-roads with something that heavy, for fear of getting stuck and not being able to unstick it through main strength and awkwardness, but I ride on a lot of dirt roads, and the usual street tires are just too squirrley on that packed dirt...

Seems like there weren't ever any 15" comstar rims made, so if it ends up blowing through cheap tires too fast, I might have to revisit the wire spoke conversion option.

I think a CB450C 2.15x18 front wheel will swap directly on in place of the 19" that's on there, like I did with the Hawk. Maybe an '82 GL1100 2.50x18 front wheel, too.... That'd give me a little flatter tire profile with a 4.10-18 than the 2.15 width rim does... The results of a slightly taller rear tire with a slightly shorter front should reduce trail a little (I think?). Then swapping on some leading axle forks from an 81-82 900C ought to give a little more....

In any case, none of this is going to happen for a while. I want to get the engine running and rebuild the suspension and brakes and get it road-worthy and inspected before I go haring off on this optional-but-nice-to-have stuff. :3 Just trying to plan out as much as I can in advance...

This is Chopper Charles bike from a thread in Old's Cool. He mated the stock hub that had been a 16'er to the plates and rim from a bike with a 17"er.
So it seems doable . Pick your rim size and mix and match.

__________________
RR's Catnip Hill to Peoria ___Loopin' Seattle to WestFest
It started with some beers __1500 miles to the Dentist
Skeedaddle to Seattle______ A 30 year old on a Three Flags Run

Do y'all have any ideas for a car tire that could replace a 130/90-16 on a shaft drive bike? A 1980 Honda CB900C, in particular. Preferably an M+S tire.

I can't go any wider hardly at all. Very very little driveshaft clearance as it is. Too bad it's not a 15"; I might be able to mount a VW tire.....

I have GTR1000 ( concours ) which I am building into a sidecar which has the same tyre size as standard. I have fitted a 175/60x16 M&S Dunlop from a BMW Mini. This clears the shaft drive as the sidewalls are much straighter even though the tyre is wider. The smaller outside diameter also lowers the gearing which is useful. There are also 165/50x16, 165/45x16 and even 165/40x16 in Europe if this helps. I will post some pics if you want.
The 16" car tyre goes on a motorcycle no problem but 15" car tyres do not fit well on 15" motorcycle wheels ( I have tried ! )